Known electrical grounding or ground fault protection (GFP) technologies commonly rely on electrically-conductive elements (i.e., electrodes) that are driven, augered, or buried a significant depth into the earth in order to effectively conduct electrical current into the earth. One example of such conductive elements is the commonly-used ground rod (or earth rod), which is typically driven or augered at least 8 feet into the earth to ensure that desired functional effectiveness is achieved. Alternative known GFP technologies use conductive elements in the form of ground mats that conduct electrical current to the ground by contacting the earth over a substantial interface area, with minimal if any ground penetration.
An ideal grounding connection maintains zero voltage regardless of how much electrical current flows into or out of the earth. The electrical resistance of the electrode-to-earth connection determines the quality or effectiveness of the grounding connection. More specifically, the lower the resistance, the more effective the grounding connection and resultant ground fault protection will be. Basic principles and conventional methods of electrical grounding and ground resistance measurement may be understood with reference to various publicly-available publications, including “Understanding Ground Resistance Testing” published by AEMC® Instruments (www.aemc.com).
The quality of a grounding connection may be improved in a number of ways, such as by: increasing the electrode surface area in contact with the earth; increasing the depth to which the ground rod is driven or augered (in cases where the electrode is a driven or augered ground rod); using multiple interconnected electrodes; increasing the moisture content of the earthen materials (soil) in the vicinity of the electrodes; improving the conductive mineral content of the earth; and/or increasing the ground surface area covered by the grounding apparatus.
The installation of driven or augered ground rods typically entails the use of specialized rod-driving or augering equipment, and even with the use of such equipment earth rod installation can be difficult due to soil conditions (for example, rock formations close to surface). Even when soil conditions are readily conducive to ground rod installation, the presence of buried utilities (e.g., gas lines, electrical power lines, water lines) can give rise to the risk of personal injury and/or the need for expensive utility repairs should such buried utilities be contacted or penetrated by ground rods during the ground rod installation process. These latter risks can be mitigated or avoided by the use of ground mats not having earth-penetrating elements, but such devices may have less than desired or optimal functional effectiveness.